Science China Materials最新文献

Carbon fiber reinforced polymer composites (CFRPs) possess contrastingly high strength but low toughness, which limits their application under special circumstances, such as high stress, cryogenic temperatures, or vibration. The chemical inertness and smooth surface of carbon fiber (CF) are the main reasons behind the low toughness of CFRPs, characterized by poor interfacial performances, including low strength and low toughness. Biological organisms possess structures or chemical compositions that contribute to exhibiting strong interfacial adhesions. Herein, we construct a mussels-inspired supramolecular stress buffer (i.e., Fe(III)-tannic acid buffer, Fe-TA buffer) on CF to distribute stress and improve the interfacial performances and toughness of CFRPs. The Fe-TA buffer can improve interfacial performances by rough biomimetic interfacial structure, introducing multiple supramolecular interfacial interactions and improving interfacial wettability, ultimately resolving the common issue of low toughness in the CFRPs. In the presence of Fe-TA buffer, the interfacial shear strength (IFSS) value and mode II critical strain energy release rate (G_IIC) value are enhanced by 17.0% and 41.8%, respectively. This research provides a design for a stress buffer between resin matrix and inorganic enhancer which results in high interfacial strength and toughness.

The rapid development of supercapacitors and wearable devices has allowed the construction of integrated self-powered wearable devices. However, most current research focuses on increasing supercapacitor capacity and the sensitivity of sensors, overlooking the self-powered and integration of one single device. In this study, the editable, flexible yarn-based supercapacitor (FYSC) and an integrated self-powered wearable sensor (SPWS) were constructed based on one yarn. The FYSC demonstrated adjustable capacitive behaviors by controlling the electrode reduction degree, electrode spaces, and integration. The supercapacitors exhibit a high specific capacitance of 1.82 F cm⁻³, 92.57% capacity retention after 5000 cycles, and stable performance under static and dynamic strain conditions. Additionally, the integrated SPWSs demonstrated the accuracy and sensitivity in discriminating bending magnitudes. The SPWSs further present the accuracy and stability in recognizing human physiological activities (joint motions of finger, wrist, knee, and elbow, respiration, and handwriting). The proposed strategy offers a practical approach to developing energy storage systems with customizable functionality. More importantly, the self-powered devices realized the integration of supercapacitors and sensors would facilitate the seamless integration of 1D functional yarns into wearable electronics.

The development and utilization of clean energy have emerged as indispensable technologies within contemporary societal structures, and the development of photo-rechargeable lithium-ion batteries (PR-LIB) holds new promise for simultaneously eliminating solar energy volatility limitations and realizing battery self-charging. In this study, we present photoactive electrodes consisting of lead-free bismuth-based hybrid perovskite that combine the dual functions of photovoltaic conversion and energy storage. It was found that the PR-LIB based on this electrode increased the discharge capacity of the battery from 236.0 mA h g⁻¹ in the dark to 282.4 mA h g⁻¹ (a current density of 50 mA g⁻¹) with a growth rate of 19.7% under light conditions. The photogenerated carriers generated by the methylammonium bismuth iodide (MBI) effectively accelerated the charge transfer and lithium-ion diffusion, which contributed to the increase of the capacity and the decrease of the charge-transfer resistance. Furthermore, the charging potential decreased by 0.1 V (6% reduction in input power) while the discharging potential increased by 0.1 V (11.8% increase in output power) under light. This work demonstrates the potential of PR-LIB as an efficient, energy-saving battery in portable electronic devices.

Covalent organic frameworks (COFs) with polar linkages have been employed as metal-free catalysts for the oxygen reduction reaction (ORR). However, it is still a big challenge to precisely design or locate the catalytic sites for such kinds of COFs because their polar linkages always make some catalytic activity. In addition, the polar linkages are facile to bind with O₂ and oxygen-contained intermediates in the catalytic process, severely weakening the long-term stability of these COFs. In this work, we demonstrated the single metalfree catalytic sites based on the pyridine-cored COFs with nonpolar linkages (C=C bonds) to catalyze the ORR. The nonpolar linkages excluded their potential roles as catalytic sites and also circumvented the possible decomposition in the process of catalysis. By modulating the pyridine N with positive charges, the catalytic performance can be previously improved, because of the enhanced Lewis acidity of the carbon atoms next to the pyridine N, and thus favorable for the electrons transfer to the catalytic sites. The newly-synthesized charged COF showed high activity of a half-wave potential of 0.74 V with a mass activity of 4.34 A g⁻¹, which was 50 mV more positive and 1.63 times higher than those of the neutral COF. And the nonpolar linkages made the COFs display better long-term stability than other metal-free COFs. The theoretical calculation revealed that the ionization of pyridine promoted the formation of the intermediate OOH*, and thus improved the catalytic activity. This work gives us a new insight into designing single sites based on COFs.

The proper incorporation of defects in existing materials, including cationic and anionic vacancies, would act as suitable promoters for enhancing the energy efficiency of water electrolysis at large current densities, but controllably creating effective vacancies in electrocatalysts remains a formidable challenge. Here we report that a sandwich-like nanoporous hybrid catalyst consisting of double-layer nickel nitride (Ni₃N) intercalated by a metallic Ni layer is creatively synthesized through room-temperature ionized nitrogen radio frequency plasma bombardment with short reaction times. This unique strategy not only ensures good electron transfer between Ni and Ni₃N, but also provides abundant nitrogen vacancies as the active species ameliorating initial water dissociation and subsequent hydrogen adsorption as evidenced by the density functional theory (DFT) calculations, thus greatly enhancing the hydrogen evolution kinetics. Owing to the introduction of nitrogen vacancies and the synergistic interaction between Ni₃N and Ni species, the resultant catalyst exhibits excellent hydrogen-evolving activity approaching the state-of-the-art Pt catalysts, featured by considerably low overpotentials of 14 and 180 mV to achieve 10 and 500 mA cm⁻², superior to most available non-precious electrocatalysts, thus considerably facilitating the electrochemical hydrogen production at low voltages under large current density. Remarkably, this catalyst exhibits outstanding durability at large current densities (200–500 mA cm⁻²) for over 1000 h, which is in sharp contrast to most of the non-noble electrocatalysts with tens of hours of stability. This simple strategy does not involve any cumbersome synthetic procedures, paving a new avenue toward the rapid synthesis of robust hydrogen-evolving electrocatalysts for alkaline water electrolysis.

Solid-phase synthesis as a bottom-up strategy may be a superior way to integrate sophisticated functions into an ultrathin film for miniaturized devices. However, the sluggish reaction dynamics at the solid-liquid interface have been a great challenge. Herein, we present four electrochemical reactions for rapidly synthesizing length and conjugation-controlled metallopolymer monolayers. This electrosynthesis requires self-assembled monolayers as templates as a prerequisite to predefine the growth and orientation of the metallopolymers. Electrosynthesis involves a pair of redox reactions: the oxidation self-coupling of pyrene or carbazole, and the reduction self-coupling of the alkyne or vinyl, respectively. They can form conjugation-controlled connections of monomers and provide different lengths of metallopolymers. The resulting metallopolymer monolayers show similar values in thickness and theoretical molecular length, indicating that these metallopolymers stand almost vertically and uniaxially on electrodes with minimum polymer disorder. These crystalline monolayers exhibit both high modulus and conductance while presenting the memristive functions with optical and electrical binary responses as a function of the length and conjugation-controlled metallopolymer monolayers. It is highly anticipated that critical factors including reproducibility, speed, and operational simplicity with the robust design of various molecular junctions will enable rapid automated synthesis of two-dimensional semiconductors for integrated and miniaturized optoelectric devices.

The influence of hydrogen bonding on spectroscopic properties is one of the fundamental issues in the field of luminescent organic–inorganic hybrid metal halides (OIMHs). We design and prepare three OIMHs, namely, crystals 1, 2 and 3, using 2,2′-bipyridine and ZnCl₂ as starting materials. From crystals 1 to 3, the hydrogen bonding environment surrounding the 2,2′-bipyridinium cations gradually weakens, with both the dihedral angle and the number of hydrogen bonds around them decreasing progressively. Correspondingly, the blue emission belonging to the S₁ → S₀ transition of the three crystals gradually increases, with crystal 3 exhibiting the strongest blue light emission and a photo-luminescence quantum yield reaching 34.10%. In crystal 1, the dense hydrogen bonding environment of the 2,2′-bipyridinium cation results in an obvious energy transfer from S₁ to T₁. This reduces the population of the S₁ state, thereby leading to weaker blue light emission. In crystals 2 and 3, the weaker hydrogen bonding environment and smaller spatial distortion of organic cations weaken or even prevent energy transfer between S₁ and T₁, thereby enhancing blue light emission. These findings provide new insights for exploring novel luminescent OIMHs and developing more effective means of regulating their luminescence performance.

Terahertz (THz) waves have great application potential in the sixth-generation communication technology, biomedicine, spectroscopy, non-destructive testing, security inspection and other fields due to their advantages of good penetration, high safety, good coherence, high bandwidth and many other merits. At present, the research hotspots of THz photodetectors are developing towards broadband response, miniaturization, high sensitivity, low noise and room temperature operation. Terahertz photodetectors based on two-dimensional (2D) materials such as graphene, black phosphorus, transition metal dichalcogenides, and topological semimetals have attracted amazing attention for the researchers. This paper mainly discusses the recent research progress of these four types of materials in the application of terahertz photodetectors.

In recent years, wearable electrochemical sensors have been widely used for biochemical analysis. These sensors, which incorporate flexible electrodes and sensitive recognition elements on a flexible substrate, facilitate the noninvasive, in-situ, real-time, and continuous monitoring of target biochemical molecules in biofluids while maintaining high selectivity and sensitivity. This review provides a comprehensive examination of the principles guiding the selection of core components and the recent advances in wearable electrochemical sensors for biochemical markers in recent years. Initially, we outline the essential considerations in designing wearable sensors to detect biomarkers in biofluids, including sampling techniques, material selection, design parameters, recognition elements, sensing strategies, power requirements, data processing, and sensor integration. We emphasize the improved efficacy of recognition elements, which has been significantly enhanced by biotechnology and materials science developments, facilitating selective and sensitive detection of target components within complex matrices. Concurrently, incorporating nanomaterials and conductive polymers (CPs) has markedly improved the sensing capabilities of flexible electronics. Subsequently, we investigate recent progress in situ detection of biochemical markers utilizing wearable electrochemical sensors that employ advanced materials, optimized mechanical structures, and various conduction mechanisms. The notable applications stemming from these technological innovations illustrate significant improvements in sensitivity, reliability, and monitoring capabilities of wearable electrochemical sensors while enhancing user comfort. Finally, we address the current challenges and future perspectives regarding implementing clinically oriented wearable electrochemical sensors for disease monitoring and personalized medicine.